The present invention relates generally to D.C. power supplies and more particularly to overvoltage protection in one or more D.C. power supply circuits, where a plurality of D.C. power supplies may be connected together to supply power to an electronic system.
Typically, in an electronic apparatus such as a large computer for instance, in order to prevent any trouble with a power supply circuit from stopping the electronic apparatus, a plurality of D.C. power supply circuits are connected in parallel for redundant operation. Thus if one D.C. power supply fails, the other D.C. power supplies continue to supply the necessary power needed by the load.
In a conventional D.C. power supply, overvoltage protection is also provided. The D.C. power supply contains an overvoltage circuit which detects if the D.C. output voltage surpasses a prescribed voltage and if so, turns off the D.C. power supply. Where a plurality of D.C. power supply circuits are used in parallel connection, in conventional D.C. power supply circuits, if for example the D.C. output of one of the power supply circuits becomes an overvoltage and an overvoltage detecting circuit is actuated. In addition, the overvoltage of this D.C. power supply circuit also actuates the overvoltage detecting circuits of the other D.C. power supply circuits, resulting in a problem that the other D.C. power supply circuits which are not in an overvoltage state are also stopped.
Thus there is a need for a D.C. power supply with overvoltage protection, that can be used as a standalone or in combination with other D.C. power supplies. And when the D.C. power supply is used together with other power supplies, the D.C. power supply circuit having run into an overvoltage state only stops itself, and does not stop the other D.C. power supply circuits.